Simulated spacewalks, communications delays and robotics will play featured roles as U.S., European and Canadian astronauts descend to the Aquarius undersea laboratory off the Atlantic coast of Key Largo, Fla., for a second time this summer to address some of the obstacles human explorers can expect to face as they venture into deep space.

U.S. astronaut Randy Bresnik will lead the seven-day training session, NASA Extreme Environment Mission Operations 19, that is slated to get underway on Sept. 8. Joining him will be European Space Agency astronaut Andreas Mogensen, Herve Stevenin, ESA's spacewalk training lead, and Canadian astronaut Jeremy Hansen.

Aquarius, on the Atlantic seabed off Key Largo, Fla., serves as a space analog for multinational astronaut crews. NOAA

Most days will be filled with spacewalk activities outside the Florida International University-supervised Aquarius. The lab is parked on the sea floor 62 feet below the Atlantic Ocean in the Florida Keys National Marine Sanctuary and surrounded by coral reefs and always inquisitive sea life. The buoyant ocean waters render visiting astronauts "weightless," much as if they would be in free fall around the Earth aboard the International Space Station.

During their excursions, however, the men will also work with 10-minute communications delays in their exchanges with "Mission Control," just as they might expect to if they were on a mission midway between the Earth and Mars, according to Bresnik in a preview provided to NASA TV viewers this week.

"How do we work operationally throughout our spacewalks?" he explained. "When we do send a transmission?"

In late July, a three-man, one-woman Aquarius crew led by Japanese astronaut Akihiko Hoshide found that texting rather than verbal exchanges was more effective in dealing with time-delayed communications while they explored outside Aquarius.

Bresnik's crew will also assess other strategies and tools for dealing with the delays as they survey their surroundings.

One of those is "Heads Up," from ESA, a helmet display with cameras. Similar to the displays in aircraft cockpits and some automobiles, Heads Up will allow the astronaut divers to receive text from their controllers while they work with their hands uninterrupted. At the same time, the cameras will transmit images of their surroundings, allowing their distant control team to "look over the shoulders" of the astronaut divers to offer advice.

Bresnik's team will also work with a diver delivery system from Sharkmarine Technologies, Inc., an underwater sled with propulsion, navigation, sonar and cameras. The devices will serve as robot scouts.

"We will send them out autonomously, or they can carry astronauts with them -- if we want -- to use them as transportation," Bresnik explained. "They can hover in one spot."

Roving robots on Mars, like the currently-functioning Curiosity and Opportunity, perform a similar function.

"Imagine we land humans on Mars and we have five to 10 robots we can send out to areas of interest for our researchers to look at," explained Bresnik. "They go out and send back information. The astronauts, or Mission Control, look at the data and say, 'those two sites don't look that promising. These two really do. Let's go over there.'"